Subcutaneous venous access devices or ports are permanently implanted under the skin of a patient to whom it is desired to deliver repeated, periodic intravenous injections or infusions of therapeutic fluids or chemical solutions. Often such devices are used in a program of cancer chemotherapy. The injected chemicals are often toxic and, if injected under the skin rather than into a vein, will result in harm and pain to the patient or decreased absorption of the desired medication. The ports consist of a chamber-defining housing, means for suturing the housing under the skin and a self-sealing septum which allows needles to be passed through the skin and through the septum into the chamber. A catheter tube leads from the chamber and is surgically implanted into a vein. This arrangement allows a needle to be pushed through the patient's skin through the septum and into the chamber and to deliver fluid to and through that chamber into the catheter, directly into the vein. When the needle is properly inserted, the injected or infused chemical solutions are directed into the vein without reaching the skin/or subcutaneous tissue.
Individual administrations of therapeutic fluids in this manner often are accomplished over a relatively long period as infusions lasting hours or days. An infusion pump is often used to supply the fluid under pressure at precise delivery rates. During this time, it sometimes occurs, because of patient movement or otherwise, that prior conventional needles work themselves up and sometimes out of the septum, resulting in the harmful and painful injection of the fluid under the skin of the patient and decreased absorption of the desired medication.